The overall objectives are to clarify the physiological functions and pharmacological actions of hormones affecting calcium metabolism and to relate this information to problems in diagnosis and treatment of diseases. Principal attention is directed at parathyroid hormone (PTH) and thyrocalcitonin (TC) and their interrelations with the adrenal gland, gastrointestinal hormones, and vitamin D. Specific current projects include: 1. Chemical studies on rat TC. Preparation of additional supplies of pure rat TC. 2. Improvement of radioimmunoassay for rat TC. 3. Determination of species crossreactivity of TC's utilizing the immunoperoxidase method. 4. Development of antisera to human TC. 5. Effects of age, strain, sex, and diet on C-cells and immunoassayable serum TC in rats. 6. C-cell hyperplasia and concentration of TC in thyroid glands and peripheral blood of chronically parathyroidectomized rats. 7. Mechanisms responsible for increase in thyroid C-cell count and TC in thyroid gland and serum of rats goitrous from iodine deficiency. 8. Bone structure in goitrous Fischer rats. 9. Measurement of effect of secretagogues in TC secretion in rats by radioimmunoassay. 10. Effect of chronic ethanol ingestion on rat thyroid C-cells. 11. Effects of beta-adrenergic drugs on bone and on blood Ca. 12. Effect of gastrin deficiency in pigs on TC secretion. 13. Effect of feeding on blood TC and gastrin levels in rats. 14. TC in lactating rats. 15. Protective effect of TC against experimental cardiovascular and renal calcification. 16. Mechanisms of degradation of rat TC by rat tissues. 17. Adrenal factor that increases hypocalcemic response to parathyroidectomy.